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vmsplice: relax alignement requirements for SPLICE_F_GIFT

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It seems there is no fundamental reason to limit vmsplice()
SPLICE_F_GIFT to page aligned chunks.

All helpers are prepared to cope with offsets in page.

This limitation makes vmsplice() API very impractical in the zero-copy
land.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Changli Gao <xiaosuo@gmail.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Eric Dumazet
2012-04-04 11:08:51 +02:00
committed by Jens Axboe
parent a637120e49
commit bd1a68b59c
1 changed files with 2 additions and 2 deletions
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4
fs/splice.c
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@@ -1385,7 +1385,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
*/ */
static int get_iovec_page_array(const struct iovec __user *iov, static int get_iovec_page_array(const struct iovec __user *iov,
unsigned int nr_vecs, struct page **pages, unsigned int nr_vecs, struct page **pages,
struct partial_page *partial, int aligned, struct partial_page *partial, bool aligned,
unsigned int pipe_buffers) unsigned int pipe_buffers)
{ {
int buffers = 0, error = 0; int buffers = 0, error = 0;
@@ -1623,7 +1623,7 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
return -ENOMEM; return -ENOMEM;
spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
spd.partial, flags & SPLICE_F_GIFT, spd.partial, false,
pipe->buffers); pipe->buffers);
if (spd.nr_pages <= 0) if (spd.nr_pages <= 0)
ret = spd.nr_pages; ret = spd.nr_pages;